Really depends on what you want to do with the data, however, to add all your entry's to an array.
Simply change the names of all your fields to Name="Choice[0]", Name="Choice[1]", etc.
Instead of having four seperate variables, you'll now have one array with four entries.
like:
<BR>
<INPUT NAME="Correct_Answer" TYPE="RADIO" VALUE="0">
<INPUT NAME="Choice[0]" TYPE="TEXT" SIZE="50">
<BR>
<INPUT NAME="Correct_Answer" TYPE="RADIO" VALUE="1">
<INPUT NAME="Choice[1]" TYPE="TEXT" SIZE="50">
<BR>
<INPUT NAME="Correct_Answer" TYPE="RADIO" VALUE="2">
<INPUT NAME="Choice[2]" TYPE="TEXT" SIZE="50">
<BR>
<INPUT NAME="Correct_Answer" TYPE="RADIO" VALUE="3">
<INPUT NAME="Choice[3]" TYPE="TEXT" SIZE="50">
<BR>